PROJECT SUMMARY/ABSTRACT Progression of SARS-Coronavirus-2 (SARS-CoV-2) infected patients to life threatening disease may result from a virus-mediated, dysregulated immune response associated with excessive production of inflammatory cytokines, cytokine release syndrome. In this proposal we seek to identify therapeutics and knowledge of Coronaviruses that will counteract the disruption in cytokine signaling pathways involved in effective host defense. We contribute to the urgent need for therapeutics that inhibit SARS-CoV-2 infection using pathway specific reporter cells to screen for therapeutically active compounds that restore cytokine signaling. Our pathway specific screens are a component in SBP-wide initiative to develop therapeutics that limit severe COVID-19. Our screening strategy selects drugs identified in libraries of pharmacologically active therapeutics that block SARS- CoV-2 lytic replication. We use cytokine pathway reporters to test these compounds in SARS-CoV-2 infection of a lung cell line and human lung organoids in BSL3 facilities. The selected candidates will undergo analysis for potential drug development. Fundamental knowledge of cytokine-regulated defense mechanisms related to Coronavirus infection limits the rational design of therapeutics and vaccines. To advance this knowledge we focus on the Lymphotoxin- ? Receptor (LT?R) and the Herpesvirus entry mediator (HVEM, TNFRSF14) pathways known to regulate anti- viral cytokines, interferons (IFN) and interleukin-1(IL1?). Together, the LT?R and HVEM pathways act as an integrated, homeostatic network that inhibits virus replication yet limits tissue damaging cytokines. Two SARS- CoV-2 proteins, the Papain-like protease (PLPro, Nsp3) and Nsp9 target novel components in the TRAF3 interactome that control the NF?B transcriptome. We will determine the role of these components in the key cytokine pathways using genetic and pharmacologic approaches in a mouse coronavirus lung infection model. Together these two independent but complementary aims will provide an opportunity to help solve the SARS- CoV-2 pandemic, and protect future generations.